George, I am going to make some assumptions about your approach to "Classical" music (parens employed because Classical, though used casually in reference to "serious" music, is actually a style of composition and performance of a specific type and time period in musical history). Coming from a background of "Pop" (non-Classical) music as you are (as am I), I would suggest you first explore Baroque music---J.S. Bach, Handel, Rameau, Scarlatti, Vivaldi, Couperin, Purcell, Pachelbel, etc.
I do so for two reasons. First, it is the first music written in what we now consider "Western" tonality. The major/minor scales, which, in a seriously over-simplified manner, are attributed to Bach, credited as being the father of Western Music. And second, because Baroque music is performed in the brisk tempo of Pop songs, as apposed to the more languid Romantic music (the most well-known "Classical" period). And not just in tempo, but in the song-like structure and length of it’s compositions, I find Baroque to be the most easily accessible style of Classical music to Rockers, the perfect introduction to serious music.
For recordings of Baroque music, the Harmonia Mundi label (both French and U.S.A. branches) is as good as it gets, both in performance (mostly in "period informed" style) and sound quality. Hope you find this of help in your exploration of God’s greatest gift to mankind---music!